This invention primarily relates to a method and to an instrument for use in medical diagnosis, and in particular, to detecting and determining glucose concentration in blood.
Diabetes is a health problem affecting many individuals and its prevalence is increasing. The usual treatment for diabetes is single or multiple insulin injections daily. Insulin is available in slowly or rapidly absorbed forms, which may be injected alone or in combination. Such insulin injections have been effective in treating the disease and in prolonging life.
Presently in order to determine if insulin is needed, blood is withdrawn from a patient and is tested for glucose concentration by a litmus-type indicator test. If indicated, insulin is taken by the patient.
This type of testing has several problems. For example, the testing is periodic, and thus the administration of insulin is periodic, which can result in wide variations in glucose concentration over time and peaks in the glucose concentration. Such variations can have physiological effects which may be adverse to the patient.
It has been recognized that it is desirable to administer insulin periodically on demand and in response to changes in glucose levels. One such system is disclosed in Albisser A, "Devices for the Control of Diabetes Melletus", Proc. IEEE 67 No. 9, 1308-1310 (1979) , wherein a servo system is employed which continuously withdraws blood from a patient and analyzes the same for glucose. Using a computer or microprocessor, calculations are made from the withdrawn sample as to the need for insulin, and in response thereto, insulin is administered. This system has only been used for short periods and has a disadvantage in that the system is invasive (i.e., the patient is catheterized continuously for withdrawing blood samples).
The litmus-type system has the disadvantage in that it is invasive and the patient is periodically and repeatedly pricked for blood samples.
It is therefore an object of this invention to provide a glucose testing device which can be used to monitor a patient's glucose level continuously, if desired, so as to provide a more uniform administration of insulin and a more uniform glucose concentration in the blood over time.
It is another object to provide a glucose monitoring system which is noninvasive and does not require periodic blood withdrawal to determine glucose levels.
It is sometimes desirable to test body fluids for other constituents. For example, law enforcement officers test individuals for alcohol content of their blood using a breathalyzer. However, breathalyzer tests may be inaccurate in that non-ingested alcohol, such as in mouthwashes, will provide false results.
It is another object of this invention to provide a non-invasive diagnosis apparatus for use in determining the concentration of various constituents of body fluids, such as glucose and alcohol and drugs.
Nuclear magnetic resonance (NMR) is a diagnostic technique which is used widely for medical imaging and medical diagnosis. In NMR, the test object is subjected to a first or biasing magnetic field to align previously randomly oriented .sup.1 H protons in the nuclei and a second field or burst of energy to increase the energy of a selected nucleus. When the second magnetic field or energy source is turned off, the return to the first alignment releases energy which is detected and analyzed. This release is analyzed or processed to form an image or spectrum. From the spectrum, the presence of particular molecular bonds can be observed and associated with various molecules or materials from which the concentration of that molecule or material can be determined.
NMR machines are most frequently used for imaging sections of a human body and require large magnets, for example, superconducting magnets. The machines are therefore quite large and expensive. Furthermore, the NMR testing of fluids has required invasive sample withdrawal techniques, which sample was then tested in the larger machines.
Using such NMR machines, blood serum has been analyzed and a spectra of the .sup.1 H resonance developed. In such spectra, identifiable peaks are obtained for water, glucose and ethanol. In reported tests, blood serum has been taken from animals, placed in a container and excited so as to yield the .sup.1 H spectra, which is then analyzed. Unfortunately, NMR testings are not common nor conveniently available. The reason is believed to be that the equipment is generally large, complex and expensive, and is therefore available only at selected centers, such as hospitals, universities, and other similar research and test sites. The equipment therefore is not normally used for blood or body fluid analysis as more convenient and less expensive alternatives are available.
Another disadvantage in present NMR tests is that they are conducted on fluid samples which are withdrawn from the patient by the usual invasive techniques.
It is therefore an object of this invention to provide a more convenient NMR instrument for use in analyzing body fluid samples.
It is a further object of this invention to provide an NMR instrument for use in analyzing body fluid for glucose.
It is yet another object to provide a portable NMR instrument for use by a person having diabetes to analyze his blood for glucose concentration.
It is yet a further object to provide an NMR instrument for use by a diabetic in noninvasively analyzing his blood serum for glucose concentration.
It is a still further object of the invention to provide an NMR method and apparatus to test for other substances, for example, alcohol and drugs.
These and other objects of this invention will become apparent from the following disclosure and appended claims.